| 基于抛物线密度模型的频率域三维界面反演及其在川滇地区的应用 |
| |
| 引用本文： | 张恩会,石磊,李永华,王谦身,韩长武.基于抛物线密度模型的频率域三维界面反演及其在川滇地区的应用[J].地球物理学报,2015,58(2):556-565. |
| |
| 作者姓名： | 张恩会 石磊 李永华 王谦身 韩长武 |
| |
| 作者单位： | 1. 中国地震局地球物理研究所, 北京 100081;
2. 中国科学院地质与地球物理研究所, 北京 100029;
3. 中国石油西部钻探苏里格气田项目经理部, 鄂尔多斯乌审旗 017300 |
| |
| 基金项目： | 地震行业专项(201408014);中国地震局地球物理研究所基本业务专项(DQJB12B14);地下信息探测技术与仪器教育部重点实验室(中国地质大学,北京)开放课题项目(GDL1203)联合资助 |
| |
| 摘 要： | 密度界面反演作为了解地球内部结构的一种重要方法,长期以来都是重力学研究的主要内容.本文结合抛物线密度模型及频率域算法的优点,将抛物线密度函数应用于Parker-Oldenburg算法,经过理论推导得到了抛物线密度模型的频率域公式,从而建立了基于抛物线密度模型的三维密度界面重力异常正反演的算法和流程.理论模型数据试验表明本方法快速、有效,适用于大多数浅部比深部增加更快的实际地壳密度.研究中还利用该方法对川滇地区重力异常进行了反演,获得了该区的莫霍面深度分布,并与接收函数研究结果进行对比分析,进一步验证了本文方法的正确性和有效性.
|
| 关 键 词： | 抛物线密度模型 频率域 界面反演 川滇地区 |
| 收稿时间： | 2014-04-24 |
3D interface inversion of gravity data in the frequency domain using a parabolic density-depth function and the application in Sichuan-Yunnan region |
| |
| ZHANG En-Hui;SHI Lei;LI Yong-Hua;WANG Qian-Shen;HAN Chang-Wu.3D interface inversion of gravity data in the frequency domain using a parabolic density-depth function and the application in Sichuan-Yunnan region[J].Chinese Journal of Geophysics,2015,58(2):556-565. |
| |
| Authors: | ZHANG En-Hui;SHI Lei;LI Yong-Hua;WANG Qian-Shen;HAN Chang-Wu |
| |
| Institution: | 1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;
2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
3. CNPC Xibu Drilling Engineering Sulige Gas Field Development, Ordos Uxin Qi 017300, China |
| |
| Abstract: | As an important way to reveal the internal structure of the earth, inversion of the density interface is a main subject of gravity research for a long time. Inversion of field data in the frequency domain provides a quick and efficient data analysis method. Combining the advantages of the frequency domain and parabolic density function, this paper presents a processing method for gravity anomaly data of a three-dimensional underground interface using parabolic density-depth function in the frequency domain.The method we used to make forward modeling of the gravity anomaly is based on the algorithm proposed by Parker and Oldenburg which uses constant density contrast. We substituted the constant density function in gravity forward formula for the parabolic density function. Then the Fast Fourier Transform (FFT) was applied to both sides of the equation. We derived the gravity anomaly formula of 3D density interface with parabolic density contrast after calculating the involved integral. To invert the density interface depth, an iterative algorithm was preformed to adjust the interface depth step by step until the difference between the theoretical anomalies and observations reduced to the threshold value. In addition, in order to avoid the divergence of the algorithm which is difficult to avoid for the calculation in the frequency domain, we also added a low-pass filter to the codes.We applied our method to a theoretical model which has 91×71 grid data with 10 km interval in x-axis and y-axis, and a complex 3D interface with parabolic density contrast variation in depth. In the synthetic test, we compared the method proposed in this paper with the constant, exponential and binomial functions. Besides the points with acute topography fluctuation, the results show that the inversion using parabolic function provides good and stable estimates of the interface depth of the theoretical model with RMS 0.02 km, and that the constant density function inversion gives the worst estimate of the theoretical model. According to the comparison, the choice of density parameters is a key factor in interface inversion. For the density of real situation, which varies more rapidly at smaller depth and less rapidly at larger depth, the method provides better approximations to density interface depth. In addition, we applied our method to invert the satellite regional gravity anomaly data with 10 km interval in x-axis and y-axis for the Sichuan-Yunnan region, which has complex geological structures with a large number of major faults, and negative gravity anomalies varying from -540~-90 mGal. We applied the method to invert the Moho depth below this region using reference level 35.5 km and density contrast -0.63 g·cm-3 at the earth surface with attenuation coefficient 0.0018. We compared the result with receiver function from Li et al. (2014) and other geological information. The differences between results of receiver function and our method at most seismic stations are less than 6 km. Therefore the Moho discontinuation derived from this method shows good correlation with the results of receiver function, other prior geophysical and geological information. Density contrast interface inversion is one of the primary subjects in gravity field research for understanding the earth's interior structure. This work combines the merits of the parabolic density model and the algorithm in the frequency domain, and applies the parabolic density function to the Parker-Oldenburg forward modeling and inversion algorithm. The tests on synthetic data and real data prove the new approach is rapid and effective. By inverting gravity anomaly data using this new approach, we obtained the Moho depth distribution in the Sichuan-Yunnan area, which shows that the Moho interface is shallow in the southeast but deep in the northwest. The Longmen Shan fault zone is a transition zone of the Moho depth ranging from 42 km to 58 km. |
| |
| Keywords: | Parabolic density-depth function Frequency domain Interface inversion Sichuan-Yunnan region |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球物理学报》浏览原始摘要信息 |
| 点击此处可从《地球物理学报》下载免费的PDF全文 |
|
